Plastic cards containing personalized information have become ubiquitous components of many aspects of modem life. For example, credit cards and debit cards are used to purchase goods and services, identification cards provide their holders with access to restricted areas, and ATM cards enable patrons to conduct monetary transactions with financial institutions. Personal information of the card holder that pertains to the transaction to be performed, e.g. account numbers, identification data, etc., is stored in the card. The storage mechanism can be a magnetic stripe on the card. In the case of a smart card, the information is stored in an electronic memory within a chip embedded into the card, either in lieu of or in addition to a magnetic stripe.
Many cards of these types have a size which conforms to the international standard ISO/IEC 7810. This standard defines a card having a nominal width of about 86 mm, a nominal height of about 54 mm, and a nominal thickness of 0.76 mm. Cards of this size are well known and readily adapted to be carried in a holder's wallet, pocketbook, purse or the like.
Recently, plastic cards having a smaller size than this standard format have become popular. Such cards are sometimes known as “mini cards”. Examples of such cards are depicted in U.S. Pat. No. 6,471,127 and D467,247. For instance, a mini card might have a width of 66 mm and a height of 40 mm. The card can also have a non-standard shape, as shown, for example, in U.S. Patent No. D462,966.
One of the advantages of the smaller size of the mini card is that it can be easily carried with other items commonly found on a person, such as a set of keys. For this reason, as illustrated in the previously cited patents, the mini card may be provided with a hole that enables it to be attached to a key ring. Typically, the hole might be located at one corner of the card.
The ability to attach the mini card to other everyday items can result in stresses being placed upon the card that are not typically encountered by standard format cards. For instance, when not in use, a standard card is often carried in a protective environment, such as a wallet or a purse. In contrast, a mini card attached to a key ring is likely to be subjected to much more stress and abrasion. Even the simple acts of hanging the keys on a hook or turning a key in the ignition of a motor vehicle can cause the mini card to be flung against other objects. Of particular significance is the stress that is placed upon the area around the hole that serves as the point of attachment to the keys or other external objects. Over time, the periphery of the hole will be subjected to a significant amount of abrasion. Furthermore, the corner of the card where the hole is located will undergo an appreciable amount of torque stresses, due to normal use.
A conventional plastic transaction card is constructed as a multi-layer structure. A core layer made of Teslin® (a polyolefin-based microporous film) is sandwiched between two PVC printed layers. Transparent PVC overlay layers outside of the printed layers form the exterior surfaces of the card. Although superior to a card made only with PVC layers, this construction still results in a relatively brittle structure that constrains the durability of a mini card. The flexure and torque that is experienced by the mini card can lead to cracking, particularly in the vicinity of the keyhole.